The present invention is directed to integrated circuits, and, more particularly, to an integrated System-on-Chip (SoC) circuit that supports both internal and external regulators.
Core logic circuits and analog circuits on System-on-Chip (SoC) semiconductor devices are powered by voltage regulators that can be embedded in the semiconductor device as an internal voltage regulator or located outside of the device as an external voltage regulator. Different operations of semiconductor devices may require selection between the internal and external voltage regulators.
Product compatibility and cost reduction require both a minimum pin count and low hardware overhead used in the selection of internal and external regulators. Voltage regulation is further complicated by supporting various power modes, such as low power modes, which require turning on and off the internal and external regulators during a power-up sequence and/or power mode transition. For example, a SoC device may require providing a logic signal on a multi-function input/output (IO) pin to turn off the external regulator. In addition, the SoC device may be required to detect a power-up condition of an external regulator and turn on or off one of the internal regulators accordingly. Furthermore, a SoC device may be required to turn on an external voltage regulator when an internal voltage regulator is not powered on to drive the multi-function IO pin. Accordingly, it would be advantageous to be able to control the selection of internal and external voltage regulators and power on/off modes with a minimum of device overhead.